Acrylic films were marketed in 1967. These films exhibited high resistance to the effects of ultraviolet radiation, good retention of flexibility on exterior aging and outstanding resistance to yellowing under both heat and light exposure. The film was also resistant to common stains, such as lipstick and shoe polish, and mild acids and bases. The film was suggested as suitable for surfacing wood veneers and as a protective coating for exterior signs and siding, outdoor furniture and appliance parts.
Phenolic resin impregnated kraft paper sheets, melamine modified-phenolic resin impregnated kraft paper sheets, epoxy resin impregnated fiberglass sheets (U.S. Pat. No. 3,503,621), acrylonitrile-butadiene-styrene (ABS) sheets, polyethylene sheets (U.S. Pat. No. 3,498,626) and Dacron mat, have been used as top surface protective and decorative layers on metal framed snow skis. The advent of the high performance wood-fiberglass and fiberglass-plastic foam skis, however, has posed very serious problems for present ski surfacing systems, many of which are relatively brittle.
In most cases, the extreme flexibility of the high performance wood-fiberglass or fiberglass plastic foam ski, causes the plastic protective surface layer to crack or delaminate after strenuous use, such as ski jumping, where tremendous shear stress is placed on the ski tip, which tends to flatten upon impact.
Manufacturing problems associated with presently used top surface ski layers include poor bonding to the fiberglass reinforcing layer of ski core. This is caused, in part, by protective layer sheet shrinking or stress relieving in molding, and the inherent poor bonding properties of materials such as styrene acrylonitrile. Also, in many cases, after continuous flexing of the high performance ski, the plastic surface layer develops excessive stress whitening. There is a need then, for a material and method that will solve the above mentioned manufacturing problems, and provide a long life top surface for the new generation of high performance skis.